Understanding PHP foreach Loop Syntax and Usage

This article introduces the PHP foreach construct, describing its syntax for iterating over arrays and objects.

It first presents the two basic formats:

<code>foreach (array_expression as $value)
    statement;

foreach (array_expression as $key => $value)
    statement;</code>

Next, it demonstrates array traversal with two examples: a simple value‑only loop and a key‑value loop, showing complete PHP code snippets and the expected output.

<code><?php
$arr = array(1, 2, 3, 4, 7, 8, 9, 10, 11);
foreach($arr as $a) {
    echo $a,'<br/>'; // 1 2 3 4 7 8 9 10 11
}
?>
</code>

<code><?php
$arr = array(1, 2, 3, 4, 7, 8, 9, 10, 11);
foreach($arr as $a => $v) {
    echo 'key',$a,'== value',$v,'<br/>';
}
// key0== value1
// key1== value2
// ...
?>
</code>

Finally, the article explains how foreach can iterate over an object's public properties, providing a class definition and a loop that prints each property name and its value.

<code><?php
// Define class
class Man {
    public $name = 'LiLei';
    public $height = 178;
    public $weight = 140;
    protected $age = 30;
    private $money = 1000;
}

// Instantiate
$m = new Man();

// Iterate
foreach($m as $k => $v){
    echo $k . ' : ' . $v . '<br/>'; // $k is property name, $v is value
}
/* Output:
name : LiLei
height : 178
weight : 140
*/
?>
</code>